An operation panel for operating electronic equipment is mounted in a vehicle such as an automotive vehicle. For example, the operation panel is used for an air conditioning system, a car audio system or a navigation system. The operation panel is arranged on an operation unit in a compartment of the vehicle. The operation unit includes an operation part, which a passenger of the vehicle operates. The operation part is provided by a push operation type switch or a dial type switch. The operation part is disclosed in, for example, JP-A-H09-063393, JP-A-2006-128054 and JP-A-2000-207977. The operation part is a transmission illumination type operation part so that a passenger can recognize the operation part even at night. Specifically, a light transmission part is formed on a front surface of the operation part, and a light source for lighting up the operation part is arranged behind the light transmission part. The light source emits light to a front side of the operation part so that the light transmits the light transmission part from the light source. Here, in general, one light source corresponds to one operation part. The light source is formed of, for example, LED. In some cases, to reduce the number of the light sources, the light source is arranged at a boundary between two adjacent operation parts so that a light emitted from the light source is divided into two parts. Thus, only one light source can light up two adjacent operation parts. In this case, when the two adjacent operation parts are arranged such that a distance between one operation part and the light source is almost equal to a distance between the other operation part and the light source, illumination intensity of the operation parts is almost homogeneous. However, when the front surface of the operation panel has a certain shape, or when the operation part has a certain layout, the distance between one operation part and the light source is not equivalent to the distance between the other operation part and the light source. Thus, the illumination intensity of the operation parts is not uniform. Here, it is considered that a light source is individually mounted on each operation part, and a position of the source is individually adjusted so that a distance between the source and an operation part is uniform. Alternatively, it is considered that a driving voltage of a light source is individually adjusted in accordance with a distance between the source and an operation part. However, in these cases, it is necessary for the operation unit to include a number of light sources. Further, it is necessary to adjust each distance between the light source and the operation part individually, and/or to adjust each operation condition such as a driving voltage individually. Thus, a design and a manufacturing method are complicated.